Furuya E, Yokoyama M, Uyeda K
Proc Natl Acad Sci U S A. 1982 Jan;79(2):325-9. doi: 10.1073/pnas.79.2.325.
The kinetic properties and the control mechanism of fructose-6-phosphate 2-kinase (ATP: D-fructose-6-phosphate 2-phosphotransferase) were investigated. The molecular weight of the enzyme is approximately 100,000 as determined by gel filtration. The plot of initial velocity versus ATP concentration is hyperbolic with a Km of 1.2 mM. However, the plot of enzyme activity as a function of fructose-6-phosphate is sigmoidal. The apparent K0.5 for fructose-6-phosphate is 20 microM. Fructose-6-phosphate 2-kinase is inactivated by the catalytic subunit of cyclic AMP-dependent protein kinase, and the inactivation is closely correlated with phosphorylation. The enzyme is also inactivated by phosphorylase kinase in the presence of Ca2+ and calmodulin. The phosphorylated fructose-6-phosphate 2-kinase, which is inactive, is activated by phosphorylase phosphatase and alkaline phosphatase. The possible physiological significance of these observations in the coordinated control of glycogen metabolism and glycolysis is discussed.
对6-磷酸果糖-2-激酶（ATP：D-果糖-6-磷酸2-磷酸转移酶）的动力学特性及调控机制进行了研究。通过凝胶过滤法测定，该酶的分子量约为100,000。初始速度对ATP浓度的曲线呈双曲线，Km为1.2 mM。然而，酶活性对6-磷酸果糖的曲线呈S形。6-磷酸果糖的表观K0.5为20 μM。6-磷酸果糖-2-激酶可被环磷酸腺苷依赖性蛋白激酶的催化亚基失活，且失活与磷酸化密切相关。在Ca2+和钙调蛋白存在的情况下，该酶也可被磷酸化酶激酶失活。无活性的磷酸化6-磷酸果糖-2-激酶可被磷酸化酶磷酸酶和碱性磷酸酶激活。讨论了这些观察结果在糖原代谢和糖酵解协同调控中的可能生理意义。
